The filtering options on iTalki aren't great, especially on certain platforms. Even the lesson time windows don't reliably work. I just resort to looking at teacher profiles, although it's very inefficient. Or, just try out different teachers on a trial basis; to some degree, you can't really tell someone's style until you meet with them. Although, if you're looking for a more structured experience, filtering only for Professional teachers will at least trim down the search results.